The present invention relates to a crane, preferably a truck crane, comprising a plurality of crane elements which are movable by actuators, a crane control unit for controlling and/or monitoring the movement of the crane elements, and at least one actuating switch for actuating the actuators.
Modern truck cranes usually are provided with multiaxially tiltable control sticks, sometimes also referred to as joysticks, for controlling the diverse crane elements and/or actuators provided for the same, such as the slewing gear, the hoist gear, the telescoping drive or the luffing drive. A sensor unit usually is associated to the control sticks, by means of which the central crane control detects movements of the respective control stick, whereupon the central crane control unit converts the movement signals into control signals for the actuators. In other words, the positioning movement of the control sticks is converted into control commands for the actuators via the central crane control. The actuators frequently are of the hydraulic type and are controlled via hydraulic valves, whose movement is controlled via the control commands generated by the crane control.
In practice, such crane controls have turned out to be quite useful, but nevertheless they still need improvement in some aspects and for some applications. In particular, it would be desirable to reduce the costs of such crane controls without having to do without the various functionalities. In addition, it would be desirable to accelerate the conversion of the switch movements into actual crane movements.
Therefore, it is the object underlying the present invention to create an improved crane as mentioned above, which overcomes the disadvantages of the prior art and develops the latter in an advantageous way. Preferably, a less expensive crane control should be created, which provides for a rapid conversion of the switch movements into crane movements and offers a high safety.
In accordance with the invention, this object is solved by a crane as described herein. Preferred aspects of the invention are also described herein.
Thus, it is proposed to provide the at least one actuating switch itself with sufficient intelligence, in order to achieve an autonomous control of the respective actuators by the actuating switch alone. The actuating switch is made sufficiently intelligent, in order to control autonomously and execute a corresponding control program. In accordance with the invention, a logic module is integrated in the actuating switch, by means of which the actuators can be actuated directly by the actuating switch corresponding to a respective switch actuation. This allows a control of the actuators without interconnection of the central crane control. For this purpose, the logic module has at least one control output, via which control commands generated in the actuating switch can directly be provided to the actuators. The crane control unit merely acts as a superordinate control, which through a data transmission connection can be connected with the logic module provided in the actuating switch, in order to perform superordinate control tasks. The arrangement of the logic module in the actuating switch and the direct activation of the actuators without detour via the central crane control, can result in a lower price of the control system, in so far as various components need not be provided twice. In addition, safety is increased, as it is not necessary that a chain of components between the actuating switch and the respective actuator is present and works. The speed of conversion, with which the movements of the actuating switch are converted into crane movements, is also increased, as the control signal comes directly from the switch and need not go first through the central crane control.
As an actuating switch, there is in particular provided a multiaxially tiltable control stick which has a bus connection, in order to permit communication of the integrated logic module with the superordinate central crane control unit. It will be appreciated that a plurality of such actuating switches can be provided, in order to be able to control various actuators for various crane elements. For instance, two of such multiaxially tiltable control sticks can be provided, one of which controls for instance a slewing gear as well as a hoist gear of the crane, and the other one controls for instance the luffing gear, the boom telescoping in and out, and possibly another hoist gear.
Advantageously, the at least one actuating switch including its logic module and the bus system between switch and superordinate crane control computer as well as the drive between switch and actuator are of the redundant and preferably diversitary type. In particular, the logic integrated in the at least one actuating switch is of the diversitary type. For this purpose, the logic module can include two different types of processor, which likewise can incorporate different types of software. With regard to the bus system, which in accordance with a development of the invention is of the two-channel or multichannel type, there is advantageously likewise provided a diversitary configuration, which can for instance be implemented by an LSB bus and a CAN bus. In principle, a homogeneous configuration of the logic module integrated in the switch and/or of the bus system between switch and superordinate crane control would also be possible. The redundant and diversitary configuration, however, not only provides an increased safety, but also a better error detectability, as failures always can be traced back unambiguously.
By means of the connection of the superordinate crane control unit to the actuating switch via the aforementioned bus system, the crane control unit can provide diverse superordinate control functions which go beyond the functions provided by the logic module integrated in the switch and/or activate, modify or complete the latter. In particular, any parametrization of the respective actuating switch is possible. On the one hand, the signal generation effected by the logic module can be parametrized to the effect that a backlash of the actuating switch is avoided and 100% switch movement are always converted into 100% crane element movement. On the other hand, there can also be achieved a parametrization of the actuator travel, which differs from a 1:1 conversion of the switch movement into crane element movements. For instance, if the lover is moved abruptly, a smooth movement of the activated crane element can be achieved via an integrator. Alternatively or in addition, the crane control can also provide a reassignment of the control outputs of the logic module, so that for instance according to the individual desire of the end user the X-axis of the actuating switch can be defined as a control axis for the luffing gear and for another end user as a control axis for the hoist gear.
In accordance with a development of the invention, the at least one actuating switch can include a vibrator, which provides a feedback as to the response of the crane movement, in order give a crane operator a feeling as to when and to what extent the lever movement is converted into a crane movement. In particular, the vibrator in the actuating switch can be configured so as to be driveable and parametrizable by the superordinate crane control unit via the bus system. Via the central crane control it is determined, for instance, how strong the maximum vibration is or how fast the vibration is increasing to the maximum value.
In accordance with a development of the invention, the allocation of the axes of the actuating switch can be parametrized by the central crane control via the bus system. The functionality of the lever thereby can be modified, so that additional control tasks can be performed by the same actuating switch. The control outputs of the switch do not necessarily act only on the valves of the actuators, which usually should be controlled by the actuating switch, but the signals generated via the corresponding control outputs of the switch can be withdrawn from the central crane control unit and be used for other control tasks. Thus, the central control unit, for instance upon actuation of a corresponding change-over switch, can use the control outputs of the actuating switch, which are actually provided for telescoping out the boom, for extending sliding beams for supporting the undercarriage.
Advantageously, a ramp control of the proportional outputs of the switch can be driveable and or parametrizable by the superordinate crane control unit via the bus system in accordance with another preferred embodiment of the invention. In particular, in accordance with a development of the invention, the activation of the end stages, which ultimately also provide for an actuation of the valves of the hydraulic actuators, can also be effected by the crane control means, i.e. the control commands are rerouted via the crane control. On the one hand, this allows e.g. a reassignment of the end stage outputs.
On the other hand, the magnetic fluxes, the characteristics or the so-called dither activation can be influenced and parametrized via the bus system. Diverse characteristics can be stored in the logic module of the actuating switch. Via the crane control unit, the respective characteristic desired is activated. By means of the crane control, an integrator can also be interconnected via the bus system, which for instance converts a rupture of the actuating switch as desired into control commands for driving the actuators.
In accordance with a development of the invention, the logic module in the at least one actuating switch has a specified default setting, which for instance in the case of a failure of the central crane control provides for an operation of the actuators independent of the main computer. Upon failure of the bus system and/or the central crane control, the actuating switch can operate the crane autonomously. By means of the specified default setting, it can be ensured that in the manner of an emergency operation only quite slow crane movements or crane movements in a certain direction are possible. It can be provided, for instance, that if a signal from the bus system or from the central crane control is missing, only the slowest stage of movement can be activated. From the control logic stored in the logic module, a parametrization is selected for the emergency operation.
In accordance with a development of the invention, control commands are possible both from the actuating switch and from the superordinate crane control unit for actuating the actuators. Advantageously, the smallest control command has priority, whereby functions such as limitation of the working range, performance limitation and any hydraulic proportions and hence speeds of the individual movements can be influenced by the superordinate control. Expressed in other words this means that a limitation of the switch signals by the crane control unit can be provided. Thereby, an electronic load sensing can be achieved via a parametrization of the actuating switch. The superordinate crane control unit always limits the control signals output by the actuating switch for driving the actuators such that the available hydraulic power is appropriately distributed over the various loads. The actuation of the actuators is adapted to the available hydraulic power.
In accordance with a development of the invention, the control commands of the actuating switch and of the logic module integrated therein can be deactivated partly or completely. Via the bus system, the superordinate control can directly act on the actuators, by bridging the actuating switch or the logic integrated therein, so to speak. Radio controls and automatic controls can be implemented in this way. For this purpose, the superordinate control effects a disconnection of the logic module end stages from the actuators via the bus system, whereby the actuating switch is switched dead, so to speak. Signals from the crane control can be supplied directly to the actuators.
In accordance with a development of the invention, the logic module integrated in the at least one actuating switch is freely programmable. In particular, the logic module can include a corresponding microprocessor, into which any application programm can be loaded via the bus system. A host computer moves a control program into the logic module of the actuating switch, so that the same can execute a control algorithm as desired. In this way, autonomous control functions can be implemented in the actuating switch.